Sound-reproducing instrument



Oct. 30, 1928. f 1,689,880

H. J. KUCHENMEISTER I SOUND REPRODUCING INSTRUMENT Filed Sept. 24, 1926 2 Sheets-Sheet 1 liZVezz far;

Oct. 30, 1928. 1,689,880

, H. J. KUCHENMEISTER SOUND REPRODUCING INSTRUMENT Filed Sept. 24, 1926 2 Sheets-Sheet 2 8 Z 4 M 4 K W a 01': HIM eggzz r Patented Oct. 30, 1928.

UNITED STATES summon aonannnsl.xficnnmrmsrnn, or BERLIN, GERMANY.

SOUND-BEERODUCING INSTRUMENT.

Application filed September 24, 1926, Serial No. 137,591, and in Germany October 2, 1925.

It is known to provide the sound conduits adjustable from the outside to enable them to be set in difierentways according to the -method of operation in View.

The subject of the present invention differs from these known devices in that the sound absorbing material is so arranged in an adjustable member or slide, which may be located adjacent the casing or plate supporting the sound horn, that those surfaces of the material that come in contact so that the material presents a continuation of the sound conduit'in the horn and is open to contact by the sound waves.

According to another feature of'the invention, the sound absorbing material (for example, fiat pieces of felt) are covered with metal plates having a plurality of perfora tions, layers or pieces of material being separated from each other by a perforated metal plate or plates. 7

According to another feature of the invention, the metal plates are provided with bent flaps that partlyv obstruct a central opening formed in each layer or flat piece of material. i

In order that such sound absorbers may have different absorption capacities in two or more sound conduits provided in one and the same instrument, the adjusting means for the several absorbers maybe movably coupled to ether. Adjusting means may be arrange to be operated from the outside of the instrument and coupled with other adjusting means intended to be manipulated from the interior of the instrument.

According to another feature of the invention, the'absorbers or dampers for the individual sound conduits are of diflerent dimensions and composed of difi'erent materials.-

Another feature of the invention consists in providing the sound absorber or damper for one sound conduit with a guide through which is passed an actuating member for the other sound absorber or damper in such manner that the two absorbers or dampers can be operated simultaneously, or independently, by any appropriate means. Embodiments of the invention are illustrated in the accompanying drawing, in which:

Fig. -1 represents a section through a sound conduit equipped with one form of the sound absorbing means;

Figs. 2 and 3 show the absorber or damper in plan and vertical section respectively;

I Fig. 4 is a vertical section illustrating the manner of coupling an external adjusting means with an internally situated adjusting means for the sound absorber or damper;

Fig. 5 shows how the adjusting means for the absorbers or dampers in two conduits are coupled together and at the same time rendered independently adjustable;

Fig. 6 represents a section through an arrangement in which each of two absorbers or dam ers is adjustable separately; and

Fig. shows two absorbers or dampers adapted to be adjusted either together or separately.

Fig. 8 is an enlarged broken view illustrating more particularly the provision of the metal tongues for varying the surface of damping material open to sound contact.

In the sound conduit a (or each sound conduit when there are several) is inserted an adjustable apertured slide b of sound absorbing material, such as felt, diatomaceous earth, muslin, or similar material. Preferably the diameter of the aperture in the slide 1) is equal to the diameter of the sound conduit and the slide is of such dimensions asto exert the aforesaid damping effect, without impairing the volume and quality of the waves furnishing the pure tones. The rough inner surface 0 of the aperture in the slide absorbs the disturbing secondary noises; and the slide is arranged in a convenient position in the sound conduit, for example, directly under the casing or plate 6, as indicated in Fig. 1. I

In order to adapt the sound reproduction to the special conditions of the reproduction chamber or room and to enable secondary noises of diiferent strength to be equalized according to the prevailing circumstances, each damping slide is provided with an actuating device that is operable from the outside by traction, pressure or rotation, thus enabling the slide to be adjusted transversely of the sound conduit.

If the absorber or damper is tobe displaceable transversely of the sound conduit (1, it is advisable to leaverough not only the surfacekc of the aperture but also the annular surface on which the sound waves impinge, so that these two relatively perpendicular surfaces may be utilized for absorb-- ing the secondary noises.

By :uljusting the absorber or damper If so that it projects more or less into the free aperture of the sound conduit, a kind of tone filtration is effected, which eliminates the disturbing secondary noises without impairing the main tone. According to the character of the damping material and the sound conduit. it is possible in this way to ascertain a position in which the desired control is fully accomplished, and in which the secondary noises disappear entirely without any damping of the main tone. This adjustment is particularly to be recommended when the sound producing instrument is to be used in different reproduction chambers.

The absorber or damper illustrated by Figs. 2 and 3 comprises fiat pieces of felt I) and'metal plates f; f. The metal plate 7' separates two layers of felt and these layers 'are flanked above and below by the two metal plates 7*; f, leaving different apertures that can be brought into action at will. By

the adjuster d (Fig. 1) it is possible to bring a different aperture into position within the sound conduit corresponding to the conditions for the time being and giving the best. possible filtering'efi'ect for those conditions.

Fig. 3 shows a special arrangement for enabling the' quantity of damping material, interposed in the path of the sound waves, to be controlled or modified. Provision is made in the central aperture for the insertion of metal tongues f leaving intermediate open spaces into which the felt protrudes or swells on the application of sufficient pressure. According to the prevail ing conditions, a larger or smaller number of metal tongues'is left standing, and thus a larger or smaller number of walls of felt brought into action. The open spaces formed by said tongues in the upper half of the absorber or damper are staggered in relation to those in the lower half in order to obtain the best possible damping effect.

Where there are several sound conduits, the various absorbers or dampers for the same are preferably coupled together, but so that they can also be adjusted independently.

In the arrangement illustrated by Fig. 4, each of the adjusting rods (Z is furnished at its inner end with a pin '5, and a handle h mounted on said pin'is adapted to be moved in a rail or guide provided on the plate 6. By this means, each of the externally adjustable rods d is coupled with another adjusting device it to be manipulated from the interior of the apparatus.

F moving the knob setting the absorber or damper by means of In the embodiment according to Fig. 5,

only one external adjusting rod (Z, is used for two dampers or absorbers b 6 This rod is pivoted at m to a double lever ch, to which rods d oZ attached to the dampers are connected in turn. Said last mentioned rods carry at their inner ends handles 72. 72 adapted to move in slots Z 'Z in rails 13, 76,. Another position of the double lever (Z is marked by a dot-and-dash line; wherein the handle it, has been moved towards the right and the handle 7L2 towards the left. By keeping the rod (5, stationary and turning the lever about the movable pivot m, the fundamental or initial setting of each of the absorbers 0r dampers can be altered by means of the handles h,, In. In addition, both of the absorbers or dampers can be adjusted simultaneously by the rod (Z In the form of the invention illustrated by Fig. 6, a a, denote two sound conduits equipped with obsorbers or dampers b 12 as hereinbefore described. Handles d d are provided for adjusting, that is, actuating, said absorbers or dampers. Each absorber or damper can thus be adjusted independently to suit the revailing conditions by d: or cl andcausing the damping material to protrude more or less into the path of the sound. V

According to Fig. 7, the damper?), is made thicker than (that is to say, of different external dimensions from) the other damper b The same purpose can, however, be served by using materials of different natures. This measure is particularly advantageous in cases Where diflerences in'resonance, due to difference in the material, form, and the like, of the tone-producing 'diaphra s, have to be equalized, and in cases w ere it is desired to modify the volume of tone in one or both sound conduits.

In order to facilitate manipulation, the handle, in the arrangement according to Fig.7, for the absorber 6,, is made tubular, as shown at 1' and the handle (Z, for the absorber b passes through said tube, so that both handles may be grasped at the same, time and actuated simultaneously, or grasped separately and actuated independently of each other. Reference n denotes distance-transmission means (operating by traction in the case of cords, and by traction and pressure in the case of rods) to enable the absorbers to be actuated from a. distance, for example, the listeners arm chair. In this way, the degree of damping and the mutual relation of damping in the sound conduits can be modified at will while the instrument is playing.

Manifestly, distance-transmission means may be applied to the various forms of the invention herein described, and although reference is made specifically to instruments having a single-sound conduit or two'sound conduits the invention is equally applicable to an. instrument having three or even more sound conduits and a corresponding number of absorbers or dampers. Further, variations in the construction, arrangement and operation of the absorbers or dampers is easily possible without departing from the scope of the invention, for which reason no limitation is intended beyond that imposed by the following claims.

Having now fully described my invention, what I claim and desire to secure by Letters Patent is 1. The combination with a sound re roducing instrument having a sound con uit, of a sound damper projecting into said conduit, said damper comprising perforated metal plates, apertured damping material between the plates, and tongues on the plates capable of being bent into engagement with portions of the wall of the aperture in the damping material.

2. In-a sound reproducing instrument, the combination with the sound conduit of damping means projecting into same, said means comprising perforated metal plates, an apertured body of damping material between the plates, tongues on the plates capable of being bent into engagement with portions of the wall of the aperture in the dampin plates or movement transversely of the sound conduit, and'meehanism by which the material, means mounting the position of the plates and damping material can be adjusted from the exterior of the instrument. I

3. In a sound reproducing instrument, the combination with the sound conduit of damping means projecting into same, said means comprising erforated metal plates, an apertured bo y of damping material between the plates, tongues on the plates capable of being bent into engagement with portions of the wall of the aperture in the dampin material, means mounting the plates or movement transversel of the sound conduit, and mechanism y which the position of the plates and damping material can be adjusted both from the exterior and the interior of the instrument.

4. In a sound reproducing instrument having a plurality of sound conduits, the combination of a plurality of damping means projecting into same and mounted for movement transversely thereof, and mechanism by which the means can be adjusted simultaneously or separately, each of said damping means comprising perforated metal I plates, apertured damping material between the plates, and tongues on the plates capable of being bent into engagement with portions of the wall of the aperture in the damping material.

In testimony whereof I aflix my signature.

unmucu JOHANNES xficasum usrm. 

